are harmless, in fact, many are good for us. >> if you're in an environment where it is too clean you could get the next infection that comes along. >> give me a deep breath. >> reporter: the doctor says our super clean life-style could be partly to blame for the rise in the number of people with allergies and asthma. >> i view the immune system as an army, and if it doesn't have anything to fight, in many cases it will fight allergens. >> dogs, cats, trees. >> reporter: she has allergies, as well as three of her friends at school. >> we can't be like a normal kid. >> reporter: recent studies give new weight to the decades-old theory that some germs help our systems, between the harmful and harmless irritants. these findings of this population shows that kids raised on cow farms had reduced risk of allergies. the findings follow a previous study in europe >> there is a link between the farming community having less of a link between the allergies, and the kids having less of them as they grow up. >> reporter: the experts say the alcohol-based sanitizers do have a place in our lives. in hospital
